(CG 4/29). Of the Error of the Manicheans concerning the Incarnation (Book 4. God, in His Revelation) (Summa Contra Gentiles) (Aquinas, Thomas, St.)

ARIUS held that Christ had no soul, but assumed flesh alone, to which the Divinity stood in the place of a soul. In this he was followed by Apollinaris. Apollinaris however was brought to confess that Christ had a sensitive soul; but he averred that the Divinity stood to that sensitive soul in place of mind and intellect (S. Aug. de haeresibus, 55).

1. It is impossible for the Word of God to be the form of a body.

2. Take away what is of the essence of man, and a true man cannot remain. But manifestly the soul is the chief constituent of the essence of man, being his form. If Christ then had not a soul, He was not true man, though the Apostle calls Him such: One mediator between God and men, the man Christ Jesus (1 Tim. ii, 5).

4. What is generated of any living being cannot be called its offspring, unless it come forth in the same species. But if Christ had no soul, He would not be of the same species with other men: for things that differ in 'form' cannot be of the same species. At that rate Christ could not be called the Son of Mary, or she His mother: which however is asserted in Scripture (Luke i, 43: ii, 33: John xix, 25).

5. Express mention is made of the soul of Christ, Matt. xxvi, 8: John x, 18: xii, 27.

9. The body stands to the soul as matter to form, and as the instrument to the prime agent. But matter must be proportionate to form, and the instrument to the prime agent. Therefore according to the diversity of souls there must also be a diversity of bodies. And this is apparent even to sense: for in different animals we find different arrangements of limbs, adapted to different dispositions of souls. If then in Christ there were not a soul such as our soul, neither would He have had limbs like the limbs of man.